A conventional air conditioning system employs evaporation heat which is absorbed by refrigerant from surroundings when the refrigerant evaporates. As the refrigerant, liquids such as ammonia, Freon, an azeotropic refrigerant mixture, chloromethyl, and so on, are generally used.
In the conventional air conditioning system, as a vaporized refrigerant, which is compressed by a compressor to a high pressure, flows through a condenser, the refrigerant exchanges heat with the outside air, and condenses into a liquid refrigerant having a high pressure. The liquid refrigerant having a high pressure is then converted into a low pressure liquid refrigerant after passing through an expansion valve or a capillary tube.
The low pressure liquid refrigerant enters an evaporator, exchanges heat with the inside air, and evaporates. Thereafter, the evaporated low pressure refrigerant enters the compressor to complete an air conditioning cycle which is continuously repeated. The air cooled by the evaporation heat absorbed by the refrigerant in the evaporator is directed to a space or a target object by a blower fan to conduct a cooling function.
The conventional air conditioner uses refrigerant the phase of which can easily be changed, such as through condensation and evaporation, to cool a desired space or a target object.
Meanwhile, in a base station or a communication car, various wired or wireless communication equipment is installed. The communication equipment is likely to have loose connections or to break down due to the frequent generation of heat, and thus the possibility of malfunction increases. For this reason, it is necessary to cool the communication equipment all year round to ensure reliable operation thereof.
However, in the conventional air conditioning system for communication equipment, since naturally cold outside temperatures are not appropriately taken advantage of and the air conditioning system is driven only by electric power, costs are increased, and electric power is wasted.
In order to overcome these problems, the present applicant has disclosed Korean Patent Application No. 2005-14790, entitled “Air conditioner for communication equipment and controlling method thereof”. The air conditioner disclosed in this patent document employs outside air while ensuring that the air-conditioned state of an indoor space can be reliably maintained even when a component part of the air conditioner does not work. Nevertheless, this type of air conditioner encounters a problem in that the size of the outdoor module increases, and therefore, noise is generated.